The 1995 Pacific west coast bottom trawl survey of groundfish resources: Estimates of distribution, abundance, and length and age composition

Abstract

The 1995 Alaska Fisheries Science Center West Coast triennial bottom trawl survey was conducted to assess stocks of groundfish inhabiting the continental shelf waters off the coasts of California, Oregon, Washington, and British Columbia. This was the seventh survey in an ongoing series to monitor long-term trends in the distribution and abundance of these groundfish populations.

The objectives of the 1995 survey were similar to those of the previous surveys in the series. We have made minor changes in the survey design over the years. The three most recent surveys have shifted emphasis away from estimating rockfish abundance, as had been the case from 1977 through 1986, toward assessing a broader range of groundfish species. The current design also focuses upon precisely estimating the near-bottom component of the Pacific hake and juvenile (age 1+) sablefish resource. The survey encompassed the coastal waters from Pt. Conception, California, to central Vancouver Island, British Columbia (34°30'-49°40'N lat.). The depth range of the survey was extended in 1995 for more complete coverage of the habitat of shelf rockfish. The 1980-86 surveys had covered depths from 55-366 m; in 1995, we surveyed between 55 and 500 m. A total of 533 stations were occupied, of which 522 were successfully sampled. Catches included 155 different species of fish and 112 different species of invertebrates.

This report documents survey design and the methods used in 1995, summarizes biological and environmental data collected, and presents the results of standard analyses of distribution, abundance, and biological parameters for the commercially important groundfish species in the region. Data on water temperature, catch composition, relative abundance, and geographic distribution are reported. Estimates of biomass, population abundance, length composition and age composition are also presented. Data appendices are located in a separate companion volume.


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